classical has 5 distinct synonyms spread across 4 of its 8 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is nonclassical.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
of or relating to the first significant period of a civilization, culture, area of study, etc.
“classic Chinese pottery”
of or pertaining to or characteristic of the ancient Greeks and Romans, especially their art, literature, or culture
“classical mythology”
traditional genre of music conforming to an established form and appealing to critical interest and developed musical taste
4 of the 8 recorded senses carry no synonym, antonym or related term, so they are not shown above. Every sense, with its definition and examples, is on the full entry for classical.
Synonyms, antonyms and the broader and narrower relations for classical come from Princeton University’s WordNet. Full sources and licences.